Polyphenylene ether resin composition

ABSTRACT

There is provided a polyphenylene ether resin composition comprising:  
     (i) a polyphenylene ether resin;  
     (ii) a phosphoric ester; and  
     (iii) a dispersed substance having an aspect ratio of not less than about 2, and which composition has superior heat resistance and flame resistance without use of any halogen-containing flame retardant or any halogen-containing anti-dripping agent as an essential or mandatory component.

FIELD OF THE INVENTION

[0001] The present invention relates to a polyphenylene ether resincomposition. More specifically, the present invention relates to apolyphenylene ether resin composition having superior heat resistanceand flame resistance. The polyphenylene ether resin composition of thepresent invention can be used particularly suitably as a flame-resistinginsulation sheet for electric and electronic parts without use of anyhalogen-containing flame retardant or any halogen-containinganti-dripping agent as an essential component.

BACKGROUND OF THE INVENTION

[0002] A flame-resisting insulation sheet has a thickness of from about0.1 to 0.5 mm and is required to have superior heat resistance as wellas superior flame-resisting and insulation properties. As such aflame-resisting insulation sheet, a polyvinyl chloride resin-made sheethas been used extensively. However, a flame-resisting insulation sheetcomprising no halogen has been increasingly required, because of anenvironmental problem due to the influence of halogen contained in theresin. In addition, a thin sheet such as a flame-resisting insulationsheet, when burned, easily causes an undesirable phenomenon such that akindling piece of the sheet drips, the phenomenon being hereinafterreferred to as “dripping phenomenon”. In this regard, a halogen-freesheet causes the dripping phenomenon more easily than ahalogen-containing sheet.

[0003] As a technique to improve the dripping phenomenon of apolyphenylene ether resin, for example, U.S. Pat. Nos. 4,107,232,4,332,714 and 4,355,126 disclose a combination use ofpolyfluoroethylene. Each of the references referred to above isincorporated herein by reference in its entirety.

[0004] However, there is left an environmental problem, becausepolyfluoroethylene also contains a halogen (fluorine) like a polyvinylchloride resin.

SUMMARY OF THE INVENTION

[0005] Accordingly, an object of the present invention is to provide apolyphenylene ether resin composition having superior heat resistanceand flame resistance, which composition comprises neither ahalogen-containing flame retardant nor a halogen-containinganti-dripping agent as an essential or mandatory component.

[0006] The present inventors have undertaken extensive studies relatingto both the heat-resisting and flame-resisting properties ofpolyphenylene ether resin compositions. As a result, it has been foundthat a resin composition comprising a polyphenylene ether resin, aphosphoric ester and dispersed substances having a specific size canmeet said object, and thereby the present invention has been obtained.

[0007] The present invention provides a polyphenylene ether resincomposition comprising:

[0008] (i) a polyphenylene ether resin;

[0009] (ii) a phosphoric ester; and

[0010] (iii) a dispersed substance having an aspect ratio of not lessthan about 2.

[0011] The present invention also provides a flame-resisting insulationsheet containing the above-mentioned polyphenylene ether resincomposition.

[0012] Further scope of applicability of the present invention willbecome apparent from the detailed description given hereinafter.However, it should be understood that the detailed description andspecific examples, while indicating preferred embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

DETAILED DESCRIPTION OF THE INVENTION

[0013] The term “polyphenylene ether resin” used in the presentinvention means a homopolymer resin or a copolymer resin obtained byoxidation polymerizing at least one phenol compound represented by thefollowing formula (I) with oxygen or an oxygen-containing gas with theaid of an oxydative coupling catalyst,

[0014] wherein R₁, R₂, R₃, R₄ and R₅ are independently of one another ahydrogen atom, a halogen atom, a hydrocarbon group or a substitutedhydrocarbon group, provided that one of them is always a hydrogen atom.

[0015] Examples of R₁, R₂, R₃, R₄ and R₅ in the formula (I) arehydrogen, chlorine, bromine, fluorine, iodine, methyl, ethyl, n- oriso-propyl, pri-, sec- or t-butyl, chloroethyl, hydroxyethyl,phenylethyl, benzyl, hydroxymethyl, carboxyethyl, methoxycarbonylethyl,cyanoethyl, phenyl, chlorophenyl, methylphenyl, dimethylphenyl,ethylphenyl and allyl.

[0016] Examples of the phenol compound represented by the formula (I)are phenol, o-, m- or p-cresol, 2,6-, 2,5-, 2,4- or 3,5-dimethylphenol,2-methyl-6-phenylphenol, 2,6-diphenylphenol, 2,6-diethylphenol,2-methyl-6-ethylphenol, 2,3,5-, 2,3,6- or 2,4,6-trimethylphenol,3-methyl-6-t-butylphenol, thymol and 2-methyl-6-allylphenol. Among thesephenol compounds, 2,6-dimethylphenol, 2,6-diphenylphenol,3-methyl-6-t-butylphenol and 2,3,6-trimethylphenol are preferred.

[0017] The phenol compound represented by the formula (I) may becopolymerized with a polyhydric aromatic compound such as bisphenol-A,tetrabromobisphenol-A, resorcinol, hydroquinone and novolak resins toprepare a copolymer. In the present invention, the copolymer is alsocontained in the polyphenylene ether resin according to the presentinvention.

[0018] The oxidative coupling catalyst used for the oxidative(co)polymerization of said phenol compound is not particularly limited,and any catalyst having a polymerizing ability can be used. As a processfor oxidatively (co)polymerizing the phenol compound to produce thepolyphenylene ether resin, there are exemplified those disclosed in, forexample, U.S. Pat. Nos. 3,306,874, 3,306,875 and 3,257,357, JapanesePatent Publication (JP-B) No. 52-17880, and Japanese Patent ApplicationKokai (JP-A) Nos. 50-51197 and 1-304119. Each of the references referredto above is incorporated herein by reference in its entirety.

[0019] Specific examples of the polyphenylene ether resin used in thepresent invention are poly(2,6-dimethyl-1,4-phenylene ether),poly(2,6-diethyl-1,4-phenylene ether),poly(2-methyl-6-ethyl-1,4-phenylene ether),poly(2-methyl-6-propyl-1,4-phenylene ether),poly(2,6-dipropyl-1,4-phenylene ether),poly(2-ethyl-6-propyl-1,4-phenylene ether),poly(2,6-dibutyl-1,4-phenylene ether), poly(2,6-dipropenyl-1,4-phenyleneether), poly(2,6-dilauryl-1,4-phenylene ether),poly(2,6-diphenyl-1,4-phenylene ether), poly(2,6-dimethoxy-1,4-phenyleneether), poly(2,6-diethoxy-1,4-phenylene ether),poly(2-methoxy-6-ethoxy-1,4-phenylene ether),poly(2-ethyl-6-stearyloxy-1,4-phenylene ether),poly(2-methyl-6-phenyl-1,4-phenylene ether), poly(2-methyl-1,4-phenyleneether), poly(2-ethoxy-1,4-phenylene ether),poly(3-methyl-6-t-butyl-1,4-phenylene ether),poly(2,6-dibenzyl-1,4-phenylene ether) and copolymers of everydescription containing a number of the repeating units constituting theabove-exemplified resins.

[0020] Further, a copolymer of a multi-substituted phenol such as2,3,6-trimethylphenol and 2,3,5,6-tetramethylphenol with a 2-substitutedphenol such as 2,6-dimethylphenol is also contained in the polyphenyleneether resin according to the present invention.

[0021] Among the polyphenylene ether resins exemplified above, preferredare poly(2,6-dimethyl-1,4-phenylene ether) and a copolymer of2,6-dimethylphenol with 2,3,6-trimethylphenol.

[0022] The polyphenylene ether resin used in the present invention maybe a graft copolymer obtained by grafting the above-mentioned(co)polymer with a styrene compound such as styrene, α-methylstyrene,p-methylstyrene and vinyltoluene, and such a graft copolymer is alsocontained in the polyphenylene ether resin according to the presentinvention.

[0023] With respect to the polyphenylene ether resin used in the presentinvention, those having an intrinsic viscosity of from about 0.3 to 0.7dl/g, preferably from about 0.36 to 0.65 dl/g, more preferably fromabout 0.40 to 0.6 dl/g, measured in chloroform at 30° C. are preferred.When the intrinsic viscosity is too low, it may be difficult to attainno-dripping (i.e. to cause no dipping phenomenon) at the time ofcombustion, and when it is too high, the polyphenylene ether resincomposition in accordance with the present invention may be deterioratedin its molding processability. Here, the term “no-dripping” means that asample in the course of burning is not observed to drip in a flameresistance test, that is, a UL 94 vertical combustion test.

[0024] The term “phosphoric ester” used in the present invention means acompound represented by the following formula (II),

[0025] wherein R₆, R₇, R₈ and R₉ are independently of one another ahydrogen atom or an organic group having 1 to 20 carbon atoms, providedthat the case where all of R₆, R₇, R₈ and R₉ are hydrogen atoms at thesame time is excluded, R₁₀ is a divalent organic group having 1 to 20carbon atoms, p is 0 or 1, q is an integer of not less than 1, and r isan integer of not less than 0.

[0026] Examples of the organic group represented by R₆, R₇, R₈ and R₉are an alkyl group having 1 to 20 carbon atoms, a cycloalkyl grouphaving 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atomsand an alkoxy group having 1 to 20 carbon atoms. These groups may besubstituted with any substituent. Examples of the substituent are analkyl group, an alkoxy group, an alkylthio group, an aryl group, anaryloxy group, an arylthio group and a hydroxyl group. Further, as thesubstituent, a group formed by combining the groups exemplified abovesuch as, for example, an arylalkoxyalkyl group, and a group formed bybonding the groups exemplified above through an atom such as, forexample, an oxygen, sulfur or nitrogen atom, such as, for example, anarylsulfonylaryl group, are also enumerated.

[0027] Specific examples of R₆, R₇, R₈ and R₉ are methyl, ethyl, propyl,butyl, pentyl, octyl, dodecyl, ethylhexyl, trimethylhexyl, cyclopropyl,cyclopentyl, cyclohexyl, phenyl, tolyl, xylyl, nonylphenyl, naphthyl andbutoxyethyl groups. Of these, phenyl, tolyl and xylyl groups arepreferred.

[0028] As the R₁₀ group, an alkylene group derived from an alkyl grouphaving 1 to 20 carbon atoms; a phenylene group derived from asubstituted or unsubstituted phenyl group; and a group derived from apolynuclear phenol such as bisphenols are exemplified. Of these, thelatter two groups are preferred. As a particularly preferred R₁₀ group,divalent groups derived from hydroquinone, resorcinol and bisphenol-Aare exemplified respectively.

[0029] Specific examples of the phosphoric ester are trimethylphosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate,tributoxyethyl phosphate, phenyl bisdodecyl phosphate, phenybisneopentyl phosphate, phenyl bis(3,5,5-trimethylhexyl) phosphate,ethyl dipheny phosphate, bis(2-ethylhexyl) (p-tolyl) phosphate, tritolylphosphate, bis(2-ethylhexyl) phenyl phosphate, tri(nonylphenyl)phosphate, triphenyl phosphate, dibutyl phenyl phosphate, p-tolylbis(2,5,5-trimethylhexyl) phosphate, 2-ethylhexyl diphenyl phosphate,bisphenol-A bisdiphenyl phosphate, bisphenol-A bisdicresyl phosphate,bisphenol-A bisdixylyl phosphate, hydroquinone bisdiphenyl phosphate,hydroquinone bisdicresyl phosphate, hydroquinone bisdixylyl phosphate,resorcinol bisdiphenyl phosphate, resorcinol bisdicresyl phosphate, andresorcinol bisdixylyl phosphate.

[0030] Two or more kinds of the phosphoric ester may be used at the sametime. In such a case, from a viewpoint of balance between theheat-resisting and flame-resisting properties of the polyphenylene etherresin composition obtained, it is recommendable to use a combination ofa non-condensation type phosphoric ester having 0 (zero) as r in theformula (II) with a condensation type phosphoric ester having an integerof not less than 1 as r in the formula (II). As the non-condensationtype phosphoric ester (r=0), tritolyl phosphate and triphenyl phosphateare preferred, and as the condensation type phosphoric ester (r≧1),bisphenol-A bisdiphenyl phosphate, bisphenol-A bisdixylyl phosphate,resolcinol bisdiphenyl phosphate and resorcinol bisdixylyl phosphate arepreferred.

[0031] A content of the phosphoric ester in the polyphenylene etherresin composition in accordance with the present invention is preferablyfrom about 1 to 70 parts by weight, more preferably from about 2 to 65%by weight, based on 100 parts by weight of the polyphenylene etherresin. When the content of the phosphoric ester is too small, theflame-resisting property of the polyphenylene ether resin compositionobtained may be insufficient, whereas, when it is too large, theheat-resisting property thereof may be insufficient.

[0032] The term “dispersed substance” used in the present inventionmeans a component incompatible (i.e. not capable of being mixedhomogeneously) with either the polyphenylene ether resin or thephosphoric ester. Said component forms a dispersed phase, which isdispersed in a continuous phase (matrix) comprising the polyphenyleneether resin and the phosphoric ester. Examples of the dispersedsubstance are an inorganic filler, a liquid crystal polymer and apolyorganosiloxane.

[0033] Examples of the inorganic filler are calcium silicate, magnesiumsilicate, reinforcing fibers such as glass fiber, carbon fiber, aramidfiber and fibers made of aluminum or stainless steel, metal whisker,silica, alumina, calcium carbonate, wollastonite, talc, mica, clay andkaolin.

[0034] The term “liquid crystal polymer” means a polymer exhibiting aproperty of liquid crystal when melted. Said polymer is characterized inthat (i) it has a higher heat deformation temperature than that of thecontinuous phase (matrix)-forming components in the polyphenylene etherresin composition of the present invention and (ii) it is orientedeasily in a fibril form in the matrix.

[0035] As the liquid crystal polymer, there are enumerated thermoplasticliquid crystal polyesters such as, for example, VECTRA A950 (trademark)produced by Polyplastics co. Ltd, EKONOL 6000 (trademark) produced bySumitomo Chemical Co., XYDAR (trademark) produced by NipponPetrochemicals Co., and RODRUN LC3000 and LC5000 (trademarks) producedby Unitika Ltd.

[0036] The term “polyorganosiloxane” means a compound comprising atleast one structure unit selected from those represented by thefollowing formulas (III), (IV) and (V) and a structure unit representedby the following formula (VI),

SiO_(2.0)  (III)

R₁₁SiO_(1.5)  (IV)

R₁₂R₁₃SiO_(1.0)  (V)

R₁₄R₁₅R₁₆SiO_(1.5)  (VI)

[0037] wherein R₁₁, R₁₂ and R₁₃ are independently of one another analkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 10carbon atoms, and R₁₄, R₁₅ and R₁₆ are independently of one another analkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12carbon atoms, an alkoxy group having 1 to 6 carbon atoms or a hydroxylgroup.

[0038] Here, the formula (III) stands for a tetravalent structure unitexpressing non-terminal parts of the polyorganosiloxane molecule, theformula (IV) stands for a trivalent structure unit expressingnon-terminal parts of said molecule, the formula (V) stands for adivalent structure unit expressing non-terminal parts of said molecule,and the formula (VI) stands for a monovalent structure unit expressingterminal parts of said molecule. Therefore, a polyorganosiloxanecomprising both the structure unit of the formula (V) and that of theformula (VI) results in a straight chain structure, while, apolyorganosiloxane comprising the structure unit of either the formula(III) or (IV) results in a branched structure and/or a network(cross-linked) structure.

[0039] With respect to R₁₁, R₁₂ and R₁₃ in the formulas (IV) and (V), apreferred alkyl group is a methyl group and a preferred aryl group is aphenyl group. With respect to R₁₄, R₁₅ and R₁₆ in the formula (VI), apreferred alkyl group is a methyl group, a preferred aryl group is aphenyl group and a preferred alkoxy group is a methoxy group.

[0040] Specific examples of the polyorganosiloxane are a straight chainpolydimethylsiloxane comprising structure units of the formulas (V) and(VI); a polydiorganosiloxane formed by replacing a part of the methylgroups in the above polydimethylsiloxane with a phenyl group; a branchedstructure polymethylsiloxane comprising structure units of the formulas(IV), (V) and (VI); and a polyorganosiloxane formed by replacing a partof the methyl groups in the above polymethylsiloxane with a phenylgroup. In case of a polyorganosiloxane having phenyl groups as R₁₁, R₁₂or R₁₃, a preferred phenyl group content is from about 30 to 70 mole %based on the sum of R₁₁, R₁₂ and R₁₃.

[0041] The polyorganosiloxane may be used in combination with silica. Apreferred combination is a powdery mixture of a polydiorganosiloxane andsilica. As the polydiorganosiloxane used in combination with silica,preferred is that having a viscosity of from about 10 to 100000 Pa·s at25° C.

[0042] Silica contains, for example, a finely divided silica obtainedfrom fumed silica, sedimented silica and silica aerosol. Silica having asurface area of from about 50 to 400 m²/g is preferred. Also preferredis silica treated with a liquid organosiloxane compound (hereinafterreferred to as a “silica treating agent”) having a silanol group or agroup capable of being changed to a silanol group by hydrolysis.Examples of the silica treating agent are (a) a low molecular weightliquid polydiorganosiloxane, (b) a hexaorganodisiloxane and (c) ahexaorganodisilazane, which have a hydroxyl group or an alkoxy group asa terminal group. Of these silica treating agents, apolydimethylsiloxane oligomer having a hydroxyl end group and an averagepolymerization degree of from about 2 to 10 is preferred. Relating tosilica used in combination with the polyorganosiloxane, it isrecommendable to treat 100 parts by weight of silica with from 10 to 45parts by weight of the silica treating agent before blending with thepolyorganosiloxane. It is also recommendable to further treat theaforementioned powdery mixture of the polyorganosiloxane and silica withan alkoxysilane compound. As the alkoxysilane compound, those having atleast one alkoxy group having 1 to 4 carbon atoms and at least one groupselected from epoxy, amino, acryloxy, methacryloxy, vinyl and phenylgroups are exemplified.

[0043] In the case where the polyphenylene ether resin composition,particularly a thin molded product comprising said composition, isrequired to have superior tensile elongation and superiorimpact-resisting property, it is recommendable to use thepolyorganosiloxane or a mixture thereof with silica as the dispersedsubstance.

[0044] The dispersed substance in the polyphenylene ether resincomposition in accordance with the present invention has an aspect ratioof not less than about 2. When the aspect ratio is less than 2, thepolyphenylene ether resin composition obtained may be inferior in itsdripping phenomenon-inhibiting effect (anti-dripping effect). The largerthe aspect ratio, the better the anti-dripping effect. However, anaspect ratio exceeding about 100 may cause a problem such that theappearance of the molded product obtained from the polyphenylene etherresin composition is deteriorated. Here, the term “aspect ratio” meanst/d, wherein “t” stands for an average number of the longest distancebetween both (two) ends of the dispersed substance present in thepolyphenylene ether resin composition (hereinafter referred to as“average of long diameter”) and “d” stands for an average number of theshortest distance between both (two) ends thereof (hereinafter referredto as “average of short diameter”).

[0045] The aspect ratio can be measured in a manner such that a moldedproduct (for example, a sheet) obtained from the polyphenylene etherresin composition is cross-sectionally photographed by a scanningelectron microscope or a transmission electron microscope, and 20 ormore of particles (the dispersed substance) randomly extracted from thephotograph are measured for their longest both ends distances and theirshortest both ends distances, respectively, from which the respectiveaverages of a long and short diameter are calculated to obtain theaspect ratio.

[0046] In the case where the polyphenylene ether resin composition ismolded by a molding method wherein a tensile stress is applied to thefree surface of the melted resin composition, namely, the resincomposition is molded by, for example, an extrusion molding method withuse of a T die, the “longest” both ends distance of the dispersedsubstance is preferably not more than 100 μm. When the distance exceeds100 μm, there may be caused an unevenness on the surface of the moldedproduct formed from the polyphenylene ether resin composition obtained,thereby deteriorating the appearance thereof. However, in the case wherethe resin composition is molded by a molding method such as injectionmolding, heat press molding and calendering, deterioration of theappearance hardly occurs even when the “longest” both ends distanceexceeds 100 μm.

[0047] A content of the dispersed substance is preferably from about 0.2to 20% by weight, more preferably from about 0.3 to 10% by weight, basedon the total weight of the polyphenylene ether resin composition. Whenthe content is too small, the polyphenylene ether resin compositionobtained may be inferior in its anti-dripping effect, whereas, when itis too large, the polyphenylene ether resin composition obtained may beinferior in its mechanical properties such as impact resistance.

[0048] The above-mentioned respective components used in the presentinvention may be used in combination with other high molecular weightcompounds or additives such as, for example, dyes, pigments, antistaticagents, anti-oxidants and weather resistance improving agents in amanner such that the objects and the effects of the present inventionare not impaired.

[0049] Examples of said other high molecular weight compounds arestyrene based polymers such as, for example, polystyrene, high impactpolystyrene and styrene-butadiene-styrene triblock copolymer; olefinicpolymers such as, for example, polypropylene, high density polyethylene,low density polyethylene, linear low density polyethylene,propylene-ethylene copolymer, ethylene-butene-1 copolymer,ethylene-pentene copolymer, ethylene-hexene copolymer andpoly-4-methylpentene-1; copolymers of an olefin such as, for example,ethylene and propylene with a vinyl monomer such as, for example,acrylic acid esters containing, for example, methyl acrylate and ethylacrylate, methacrylic acid esters containing, for example, methylmethacrylate and ethyl methacrylate, vinyl acetate, styrene,acrylonitrile and glycidyl (meth)acrylate; polymers such as, forexample, polyvinyl chloride, polymethyl methacrylate, polyvinyl acetate,polyvinyl pyridine, polyvinyl carbazol, polyacrylamide andpolyacrylonitrile; high molecular weight compounds such as, for example,polycarbonate, polysulfone, polyether sulfone, polyethyleneterephthalate, polybutylene terephthalate, polyarylene esterscontaining, for example, U POLYMER (trademark) produced by Unitika Ltd.,polyphenylene sulfide, polyamides containing, for example, 6-nylon,6,6-nylon and 12-nylon, and polyacetal; thermosetting resins such as,for example, polyimide, polyamidimide, phenol resin, alkyd resin,unsaturated polyester resin and diallyl phthalate resin; silicone resinsand fluorocarbon resins.

[0050] A process for producing the polyphenylene ether resin compositionin accordance with the present invention is not particularly limited andmay be any of those known in the art. The process contains, for example,a solution-blending process and a melt-kneading process. Of these, amelt-kneading process is recommendable. As the melt-kneading process,there is exemplified a process wherein respective components mentionedabove are blended in an optional order in a mixer such as a Henschelmixer, a super-mixer, a ribbon blender and a V blender, and theresulting mixture is melt-kneaded in a kneader such as a Banbury mixer,a plastomill, a Brabender plastograph and a single or twin screwextruder. A melt-kneading temperature is usually from about 150 to 400°C., preferably from about 200 to 350° C.

[0051] A process for producing a molded product of the polyphenyleneether resin composition in accordance with the present invention is notparticularly limited and may be any of those known in the art. Examplesof the process for producing said molded product are an extrusionmolding method, a calender molding method, an injection molding methodand a blow molding method.

[0052] According to the present invention, there can be obtained apolyphenylene ether resin composition which comprises, a polyphenyleneether resin, a phosphoric ester and a dispersed substance having aspecific size, and which is superior both in its heat-resisting propertyand its flame-resisting property. The resin composition comprisesneither a halogen-containing flame retardant nor a halogen-containinganti-dripping agent as an essential or mandatory component.

[0053] The polyphenylene ether resin composition in accordance with thepresent invention is suitable for uses such as, for example, films,sheets, office automation instruments and electric and electronicinstruments. Particularly, a thin molded product having a thickness ofabout 1 mm or less obtained from the present polyphenylene ether resincomposition can be used suitably as sheets or films for electric andelectronic parts. In particular, a thin molded product having athickness of about 0.5 mm or less, a thermal deformation temperature ofnot lower than 80° C. and a flame resistance of V-0 is suitable as aflame-resisting insulation sheet for electric and electronicinstruments.

EXAMPLE

[0054] The present invention is explained in more detail with referenceto the following Examples, which are only illustrative, and are notlimitative for the scope of the present invention.

[0055] Components used in Examples and Comparative Examples are asfollows.

[0056] 1. Polyphenylene Ether Resin

[0057] PPE: Poly(2,6-dimethyl-1,4-phenylene ether), its intrinsicviscosity measured in chloroform at 30° C. being 0.46 dl/g.

[0058] 2. Block Copolymer (Other High Molecular Weight Compound)

[0059] SBS: Styrene-butadiene-styrene triblock copolymer, a trade markof CARIFLEX TR1101, produced by Shell Chemical Company.

[0060] 3. Phosphoric Ester

[0061] P-1: Triphenyl phosphate, produced by Daihachi Chemical IndustryCompany.

[0062] P-2: Resorcinol bisdiphenyl phosphate, a trade mark of CR733S,produced by Daihachi Chemical Industry Company, its phosphorus contentbeing 10.7% by weight, which corresponds to a compound represented bythe formula (II), wherein R₆, R₇, R₈ and R₉=phenyl, p=1, q=1 and r=1.

[0063] 4. Dispersed Substance

[0064] Xonohige: Inorganic filler having a chemical formula of6CaO·6SiO·H₂O, produced by Ube Materials Company.

[0065] Wollastoniote: Inorganic filler produced by Hayashi Kazsei co.Ltd

[0066] GF: Glass fiber, a trade mark of TP35, produced by Nippon SheetGlass Co., Ltd.

[0067] LCP: Liquid crystal polymer, a trade mark of RODRUN LC5000,produced by Unitika Ltd.

[0068] SIP: Mixture comprising epoxy group-containing alkoxysilane,silica and polydiorganosiloxane, a trade mark of DC4-7051, produced byDow Corning Asia

[0069] Evaluation methods of the physical properties are as follows.

[0070] 1. Thermal Deformation Temperature

[0071] The thermal deformation temperature used as a measure for heatresistance was measured under a load of 1.81 MPa according to ASTM D648.

[0072] 2. Tensile Elongation

[0073] The tensile elongation was measured at 23° C. according to ASTMD638.

[0074] 3. Izod Impact Strength

[0075] A notched Izod impact strength was measured at 23° C. accordingto ASTM D256.

[0076] 4. Flame Resistance

[0077] The polyphenylene ether resin composition was press molded toobtain respective test pieces of 0.4 mm and 0.3 mm in thickness. Usingthe test pieces obtained, the UL 94 vertical combustion test was carriedout. In the evaluation of the flame resistance, the term “not comingunder” means that the burning period of time is more than thatprescribed under the UL-94 vertical combustion test, or that the testpiece burns to a clump, and the term also expresses an evaluation thatis inferior to V-0, V-1 and V-2.

[0078] 5. Appearance

[0079] The polyphenylene ether resin composition was molded with asingle screw extruder having a screw diameter of 30 mm to obtain a sheethaving a thickness of 0.3 mm. The sheet was visually evaluated on thebasis of the following criteria.

[0080] Good: No appearance deficiency was observed.

[0081] Bad: Appearance deficiency was observed.

[0082] 6. Aspect Ratio

[0083] (1) With respect to the aspect ratio relating to the dispersedsubstance of inorganic fillers, a molded product having a thickness of0.3 mm obtained by press-molding the polyphenylene ether resincomposition was cross-sectionally photographed by a scanning electronmicroscope. Not less than 20 of the dispersed particles were extractedrandomly from the photograph, and their longest both ends distances andshortest both ends distances were measured to calculate the aspectratio, i.e. a ratio of respective average values=average value of thelongest both ends distances/average value of the shortest both endsdistances.

[0084] (2) With respect to the aspect ratio relating to the dispersedsubstance of liquid crystal polymers, an ultra-thin slice obtained bycutting a press-molded product of the polyphenylene ether resincomposition with a microtome was dyed with osmium tetroxide, and thenphotographed by a transmission electron microscope. Not less than 20 ofthe dispersed particles were extracted randomly from the photograph, andtheir longest both ends distances and shortest both ends distances weremeasured to calculate the aspect ratio, i.e. a ratio of respectiveaverage values=average value of the longest both ends distances/averagevalue of the shortest both ends distances.

[0085] (3) With respect to the aspect ratio relating to the dispersedsubstance of silicone compounds, an ultra-thin slice obtained by cuttinga press-molded product of the polyphenylene ether resin composition witha microtome (not dyed) was photographed by a transmission electronmicroscope. Not less than 20 of the dispersed particles were extractedrandomly from the photograph, and their longest both ends distances andshortest both ends distances were measured to calculate the aspectratio, i.e. a ratio of respective average values=average value of thelongest both ends distances/average value of the shortest both endsdistances.

Example 1

[0086] Respective components in their blending proportions (parts byweight) as shown in Table 1 were fed from a hopper of a twin screwkneading machine (TEM-50A manufactured by Toshiba Machine Co.) set at acylinder temperature of 260° C. and a screw rotation of 200 rpm andmelt-kneaded to obtain respective resin compositions in the form ofpellets. The pellets were press-molded to obtain test pieces of 0.4 mmand 0.3 mm in thickness, respectively. Evaluation results of these testpieces are as shown in Table 1.

[0087] The foregoing pellets were extruded through a single screwextruder having a screw diameter of 30 mm with a T die of a 0.5 mm widelip at an extrusion temperature of 260° C., thereby obtaining a sheethaving a thickness of 0.3 mm. The appearance thereof was evaluated.

Examples 2 to 6 and Comparative Examples 1 and 2

[0088] Example 1 was repeated, except that respective components intheir blending proportions (parts by weight) as shown in Tables 1 and 2were used. Evaluation results are as shown in Tables 1 and 2. Here, inComparative Examples 1 and 2, no dispersed substance was used, such thatthe dripping phenomenon was observed on three test pieces of ComparativeExample 1 (out of 5 five pieces thereof tested) and two test pieces ofComparative Example 2 (out of 5 five pieces thereof tested),respectively. TABLE 1 Example 1 2 3 4 5 6 Blending proportion (parts byweight) PPE 100 100 100 100 100 100 P-1 22 22 22 22 22 6 P-2 0 0 0 0 015 Xonohize 3 0 0 0 0 3 wollastonite 0 3 0 0 0 0 GF 0 0 3 0 0 0 LCP 0 00 3 0 0 SIP 0 0 0 0 6 0 SBS 14 14 14 14 14 2.5 Average of long 1.5 30280 2 0.3 1.5 diameter(micron m) Average of short 0.1 5 10 0.6 0.1 0.1diameter(micron m) Aspect ratio 15 6 28 3.3 3 15 Thermal Deformation 9595 96 94 94 111 temperature (Celsius) Tensile elongation 35 35 60 27 11060 (%) Izod impact 22 12 16 19 50 3 Strength (kJ/m²) Flame resistance0.4 mm Thickness V-0 V-0 V-0 V-0 V-0 V-0 0.3 mm Thickness V-0 V-0 V-0V-0 V-0 V-0 Appearance of Good Good Bad Good Good Good sheet

[0089] TABLE 2 Comparative Example 1 2 Blending proportion (parts byweight) PPE 100  100  P-1 22  6 P-2  0 15 Xonohize  0  0 wollastonite  0 0 GF  0  0 LCP  0  0 SIP  0  0 SBS 14   2.5 Average of long — —diameter (micron m) Average of short — — diameter (micron m) Aspectratio — — Thermal deformation 92 109  temperature (Celsius) Tensileelongation 70 16 (%) Izod impact 42  3 strength (kJ/m²) Flame resistance0.4 mm Thickness V-2 — 0.3 mm Thickness NCU V-2 Appearance of Good —sheet

We claim:
 1. A flame-resisting insulation sheet comprising apolyphenylene ether resin composition, which resin composition contains:(i) a polyphenylene ether resin (ii) a phosphoric ester; and (iii) adispersed substance having an aspect ratio of not less than about 2,wherein the sheet has a thickness of not more than 0.5 mm.
 2. Theflame-resisting insulation sheet according to claim 1, wherein thedispersed substance in the resin composition has a longest both endsdistance of not more than 100 μm.